A common disease, especially among elderly human patients, involves the resistance of blood vessels to the flow of blood resulting in a lowering of the amount of oxygen delivered to muscles and skin at extremities of the body such as the hands or feet and giving rise, for example, to the sensation of cold feet and intermittent claudication.
Several drugs are known which when administered to patients suffering from such vascular diseases will increase blood flow by decreasing the resistance of the blood vessels. Some of these known drugs have unwanted side effects which makes them less desirable than others.
Among the known drugs which are capable of reducing resistance to blood flow, called peripheral vasodilators, are nicotinic acid, which has the formula: ##SPC2##
Nicotinyl alcohol which has the formula: ##SPC3##
Isoxsuprine which has the formula: ##SPC4##
Tolazoline which has the formula: ##SPC5##
Nylidrin, papaverine and cyclandelate. Of the above-named drugs, nylidrin and isoxsuprine have perhaps been more commonly administered for the relief of peripheral vascular diseases. But the search continues for vasodilator drugs which are more effective in reducing blood vessel resistance or which may have fewer side effects. Many patients who suffer from the effects of restriction to blood flow also have heart disease of some kind, and treatment with some of the known vasodilators, which also have an effect on the heart, may be too hazardous. Unwanted cardiovascular effects which have been recorded include hypertension, tachycardia, palpitations and postural hypotension. Other side effects may include headache, nausea, dizziness, nasal congestion, flushing and tingling sensations.